1. Technical Field
Several aspects of the present invention relates to an imaging device, an inspection apparatus loaded with the imaging device, and a method of manufacturing an electronic device.
2. Related Art
In order to improve portability and convenience of an electronic device such as a biometric authentication device or a digital camera, it is important to make an image sensor (imaging device) compact which captures a target object. For example, as described in JP-A-5-100186, there has been known an imaging device which becomes compact by interposing a pinhole (light transmitting region) between a micro-lens and a light sensing element, and arranging the micro-lens, the light sensing element, and the pinhole in a multiple way to correspond one to one each other.
In the imaging device in JP-A-5-100186, the light sensing element is disposed on an optical axis that connects the pinhole and the micro-lens, and thereby light of an inspection object (inspection light) which is collected using the micro-lens and travels along the optical axis is caused to be incident on the light sensing element.
In the imaging device, if a light blocking substrate formed with the pinhole is disposed to be inclined with respect to a sensor substrate formed with the light sensing element, the light sensing element is not disposed on the optical axis which connects the pinhole and the micro-lens, and light other than the inspection light is caused to be incident on the light sensing element. In order to inhibit such a problem, it is necessary to dispose the light blocking substrate and the sensor substrate to be opposite to each other at a uniform gap.
If the light blocking substrate is disposed to be close to the sensor substrate, for example, if the pin hole is formed right on the light sensing element, other than inspection light traveling along the optical axis, light other than the inspection light, which obliquely travels with respect to the optical axis, is also incident on the light sensing element. On the other hand, if the light blocking substrate and the sensor substrate are spaced apart from each other at an appropriate gap, light (inspection light) in the optical axis direction, which passes through the pinhole, is incident on the light sensing element, but light (light other than the inspection light) in an oblique direction with respect to the optical axis, which passes through the pinhole, is not incident on the light sensing element. Specifically, on an optical path of light (the above-mentioned light in an oblique direction with respect to the optical axis) other than the inspection light traveling to the light sensing element, a light blocking film formed on the light blocking substrate is present and light other than the inspection light is blocked by the light blocking film, and thereby the light other than the inspection light is inhibited from being incident on the light sensing element. Accordingly, in order to cause the inspection light to be selectively incident on the light sensing element, it is necessary to space (dispose) the light blocking substrate and the sensor substrate apart from each other at an appropriate gap. Specifically, if the gap between the light blocking substrate and the sensor substrate is set to an array pitch (approximately 50 μm to 100 μm) or more where the light sensing element is arranged, the inspection light is caused to be selectively incident on the light sensing element.
As described above, in the imaging device in JP-A-5-100186, if the light blocking substrate and the sensor substrate are disposed at a uniform gap of approximately 50 μm or more, light other than the inspection light which is a detection noise is not incident on the light sensing element, and it is possible to detect detection light with a high accuracy.